The use of automated stapling devices is well known in the context of mid- or high-volume office equipment such as copiers and printers (hereinafter generically called “printers”). Typically, a stapling apparatus downstream of the engine of a printer includes a “compiler tray,” which is a vertical or angled (i.e., non-horizontal) container for temporarily retaining sheets output from the printer. Associated with the compiler tray are any number of mechanisms for accepting or ejecting sheets in or from the container. As each multi-page document is output from the printer, the sheets thereof accumulate in the compiler tray. When the multi-page document (“set”) is completely printed, the sheets accumulated in the compiler tray are stapled, and the stapled set is then ejected from the compiler tray.
In a typical arrangement of a compiler tray, there is an effective hard surface at the bottom of the tray, against which edges of sheets in the set are placed, mainly by gravity. The bottom surface acts as an aligning surface so that, just before a staple is driven into the set of sheets, the bottom edge of the set is properly aligned, resulting in a neat stapled set.
As a practical matter, particularly with large stapled sets, it becomes difficult to maintain an aligned edge of a set prior to stapling. Buckling of sheets within the compiler tray while sheets are being accumulated can result in an unsatisfactory stapled set.